GCSE Science and Maths revision

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:sl:

i dont know what quadratics mean...so i just went with what i thought was right; thus:

6x^2 - 3x + 4x - 2 = 3
6x^2 + x -2 -3
6x^2 + x -5

probably wrong but hey...now that its done, i aint bothered to erase it.

:w:
 
please can someone provide a simple explanation to Eutrophication? It knocks me for 6 everytime. :S :S :S
 
DeepOcean said:
please can someone provide a simple explanation to Eutrophication? It knocks me for 6 everytime. :S :S :S
Click to expand...

recalling from memory, isnt it when nitrates (or whatever) are washed from land into the rivers/water causing the plants to die?

:w:
 
yeah something like that. My teacher was going on about the 'six steps' I was completely lost lol
 
:salamext:

+*Rooh*+ said:
:sl:

i dont know what quadratics mean...so i just went with what i thought was right; thus:

6x^2 - 3x + 4x - 2 = 3
6x^2 + x -2 -3
6x^2 + x -5

:w:
Click to expand...

So far correct....

then if you factorize: (6x - 5)(x + 1)= 0

either: (6x - 5)=0 or (x + 1)= 0

so: 6x = 5 or x = -1

therefore the two solutions are: x = 5/6 or -1

dont know if i explained properly but thats that
 
:salamext:

What are the uses of the following noble gases?

Helium

Neon

Argon

Krypton
 
He helium The gas is much less dense than air (lighter) and is used in balloons and 'airships'. Because of its inertness it doesn't burn in air UNLIKE hydrogen which used to be used in large balloons with 'flammable' consequences e.g. like the R101 airship disaster! Helium is also used in gas mixtures for deep-sea divers.

Ne neon just like this website! Neon gives out light when high voltage electricity is passed through it, so its used in glowing 'neon' advertising signs and fluorescent lights.

Ar argon Argon, like all the Noble Gases is chemically inert. It used in filament bulbs because the metal filament will not burn in Argon and it reduces evaporation of the metal filament. It is also used to produce an inert atmosphere in high temperature metallurgical processes, eg in welding where it reduces brittle oxide formation reducing the weld quality. Its bubbles are used to stir mixtures in steel production. Argon is the cheapest to produce.

Kr krypton Not used by superman! BUT is used in fluorescent bulbs, flash bulbs and laser beams.
 
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:sl:

DeepOcean said:
Polymerisation? All that alkanes and alkenes stuff! :S
Click to expand...

ok...bear with me cause i really have hard time explaining since its all recalling from memory.

ok so...alkanes are saturated and alkenes are unsaturated...to be honest, i dont really now what each of that means but i only know that. they are both from the family of hydrocarons. the first 4 alkanes are methane CH4, ethane C2H6, propane C3H8 and butane C5H12. the formula to find the H for alkanes is CnH(2n+2)...now onto the alkenes. alkenes are usually carbon carbon double bond. and the stuff is usually spelt with an 'e' where the 'a' is. eg. instead of ethane, it is ethene. the formula to find the H in alkenes is CnH(2n). eg. ethene C2H4 and propene C3H6. the test for alkenes and alkanes is the bromine water thingamajig. alkenes turn bromine water (a brown colour solution :?) colourless.

polymerisation...
there are monomers and polymers...you ought to know the difference between the two. a monomer is a simple molecule eg. C2H4...a polymer is a large molecules formed from simple smal molecules...i dont have an example...cause i cant remember one ^o)
and i think...if i remember correctly...only alkenes can polymerise this is because of their double bond. polymerisation is when lots of small molecules join together end to end to form a large one. these are called addtion polymers. eg. ethene...lots of ethene = poly ethene, propene...lots of propene = polypropene.

i did a google search nd found a perfect image explaining what i just said above:

polyethene.gif


the 'part of a polyethene molecule' can also be drawn like this:

thumb_Polyethene_monomer.png


:w:
 
Insulin is a hormone that regulates the amount of glucose (sugar) in the blood and is required for the body to function normally. Insulin is produced by cells in the pancreas, called the islets of Langerhans. These cells continuously release a small amount of insulin into the body, but they release surges of the hormone in response to a rise in the blood glucose level.

my 10 yr old sister has diabetes she should know.
rani
 

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